1. Field of the Invention
The present invention relates to a storage medium storing a game program executable by a computer of a game apparatus, and a game apparatus. More particularly, the present invention relates to a storage medium storing a game program executable by a computer of a game apparatus which determines whether or not objects contacts each other in a game space and performs a game process, depending on the result of determination, and a game apparatus.
2. Description of the Background Art
In so-called shooting games and action games, it is determined whether or not objects appearing in a game space contacts each other (see, for example, Japanese Patent Laid-Open Publication No. H11-47448). Japanese Patent Laid-Open Publication No. H11-47448 describes a game apparatus in which determination areas are previously set with respect to various objects, such as a player object operated by a player, a bullet, a missile or laser shot by the player object, an enemy object, a bullet, a missile or laser shot by the enemy object, and the like. The sizes, numbers, arrangements and the like of the determination areas are defined, depending on the sizes and the like of the objects. Each determination area is moved in the game space in accordance with the movement of the corresponding object. In the game apparatus, by determining whether or not these determination areas contact each other, it is determined whether or not a bullet shot from an enemy character hits a player object, for example.
Conventional liquid crystal televisions have a function of temporarily storing a program received from a broadcast station in a memory and performing image processing so as to improve the image quality before displaying the program. Such image processing is also similarly performed with respect to game images which are transmitted from a game apparatus at predetermined time intervals, in addition to a program received from a broadcast station. Therefore, when the game apparatus described in Japanese Patent Laid-Open Publication No. H11-47448 is used while being connected to a liquid crystal television, there may be a slight time lag between the execution of a game process in a game apparatus and the actual display of a game image showing the result on the liquid crystal television. Specifically, there may be a delay between the execution of a game process including the contact determination in a game apparatus and the actual display of a game image showing a game space subjected to the game process on a liquid crystal television.
Here, a problem caused by the delay will be described with reference to FIGS. 21A to 21C, assuming a case where a player object is caused to jump in a game space, for example. FIGS. 21A to 21C are diagrams showing game images representing how a player object 90 moves on a block 91 in the game space. A game apparatus determines, in units of a frame, whether or not the block 91 exists at a foot of the player object 90 so that the player object 90 can kick the block 91 (contact determination). When a player provides an operational input to cause the player object 90 to jump, then only if the game apparatus determines that the block 91 exists at a foot of the player object 90, the player object 90 is caused to jump. In the presence of the aforementioned delay, when contact determination is performed with respect to the player object 90 and the block 91 in a game space indicated by the game image of FIG. 21C, the display device displays the game image of FIG. 21A which is two frames before the game image of FIG. 21C. In this case, the following phenomenon may occur. A player who views a game image (see FIG. 21A) thinks that they can cause the player object 90 to jump since the block 91 exists at a foot of the player object 90. Actually, however, the block 91, on which the player object 90 should kick, no longer exist at a foot of the player object 90 in a game space (see FIG. 21C) in which the game apparatus is performing the contact determination, since the player object 90 has already been moved. Therefore, the player object 90 cannot be caused to jump. In other words, in conventional game apparatuses, the timing of the contact determination performed in a game apparatus may be deviated from the timing of display of a game image showing a game space which is subjected to the contact determination, resulting in an illogical game process for the player.
This problem may arise with display devices, such as plasma televisions, monitors for personal computers, projectors and the like, which are likely to cause a delay as in liquid crystal televisions. Moreover, when a game apparatus is connected to a display device via one or more devices, such as a video cassette recorder or the like, the aforementioned problem may arise since the transfer rate of a game image from the game apparatus to the display device is reduced.
Moreover, for example, when the player object 90 is moving at high speed, a player may recognize that the player object 90 is not dropping from the block 91, though the player object 90 is actually dropping from the block 91. In this manner, there may be an error between the position of the player object 90 recognized by the player who actually views it in a game image, and the actual position of the player object 90. As a result, even if the aforementioned delay does not exist, a game process performed based on the result of contact determination may be illogical for the player.